1. Field of the Invention
The present invention relates to an ultrasonic diagnostic device and an ultrasonic image generation method, and in particular, to an ultrasonic diagnostic device and an ultrasonic image generation method for generating an ultrasonic image by performing reception focusing in a different direction from the transmission direction of an ultrasonic beam.
2. Description of the Related Art
Conventionally, in the medical field, an ultrasonic diagnostic device using an ultrasonic image has been put into practical use. In general, this kind of ultrasonic diagnostic device generates an ultrasonic image by transmitting an ultrasonic beam toward a subject from the ultrasonic probe, receiving an ultrasonic echo from the subject using the ultrasonic probe, and electrically processing the reception signal.
In such an ultrasonic diagnostic device, a tomographic image of the inside of the subject located immediately below the probe cannot be observed in real time. Accordingly, for example, when inserting the needle to the target location in the subject, an ultrasonic image of the inside of the subject is generated by placing the probe immediately above a target location and the needle is obliquely inserted toward the target location from the vicinity of the probe, so that the needle is inserted while checking the position of the needle in the subject on an ultrasonic image.
However, in general, the surface of the needle is smooth. Accordingly, an ultrasonic beam having propagated through the subject from the probe is likely to be regularly reflected on the surface of the needle. In addition, since the needle is obliquely inserted toward the target location, it may be difficult to visualize the needle by capturing the specular reflection of the ultrasonic beam transmitted in the normal direction of the probe in the reception opening of the probe.
Therefore, visualizing the needle by transmitting an ultrasonic beam in a direction perpendicular to the needle instead of the normal direction of the probe and performing reception focusing has been known.
For example, JP2012-213606A discloses an ultrasonic diagnostic device that generates a first image by transmitting and receiving an ultrasonic beam in a first direction perpendicular to the element surface of a probe for the purpose of tissue imaging, generates a second image group by transmitting and receiving an ultrasonic beam in a plurality of second directions, which are different from the direction perpendicular to the element surface, for the purpose of needle imaging, generates an image in which a needle is visualized by analyzing the second image group, and combines the image with the first image.
According to the device disclosed in JP2012-213606A, since a direction perpendicular to the needle is included in the plurality of second directions, it is possible to generate an ultrasonic image in which the needle is satisfactorily visualized.